Clinical Association of Negative Lymph Nodes With Adjuvant Chemotherapy in Patients With T3N0 Rectal Cancer.

Background: The use of adjuvant chemotherapy in patients with stage T3N0 rectal cancer following total mesorectal excision (TME) is debated. This study is aimed at investigating the clinical significance of negative lymph node (NLN) counts in patients with T3N0 rectal cancer, particularly in relation to adjuvant chemotherapy. Methods: This retrospective analysis examined 311 patients with T3N0 rectal cancer who underwent radical resection at the Sixth Affiliated Hospital of Sun Yat-sen University between August 2014 and December 2021. The optimal cutoff for NLN counts was determined using receiver operating characteristic (ROC) curves. Clinicopathological characteristics and clinical outcomes were compared between the high and low NLN groups. Overall survival (OS) and disease-free survival (DFS) were used to evaluate the efficacy of adjuvant chemotherapy. Results: The optimal cutoff for NLNs was 21. Of the 311 patients, 141 were categorized into the high NLN group and 170 into the low NLN group. Patients with NLNs ≥ 21 had significantly better 5-year OS (99.3% vs. 88.2%, p < 0.05) and 5-year DFS (92.2% vs. 79.4%, p < 0.05) compared to those with low NLNs. Multivariate Cox analysis revealed that NLN count was an independent prognostic factor for OS (hazard ratio (HR) = 0.078, 95% confidence interval (CI): 0.011-0.582, p = 0.013) and DFS (HR = 0.417, 95% CI: 0.213-0.815, p = 0.011). Subgroup analysis indicated that adjuvant chemotherapy significantly improved OS (p < 0.05) and DFS (p < 0.05) in the low NLN group. Conclusion: NLN count is an independent prognostic factor in patients with T3N0 rectal cancer. Patients with low NLN counts (NLN < 21) may benefit from adjuvant chemotherapy.